MDCAT Biology MCQs

Correct answer B. A rise in carbon dioxide (H⁺) concentration

Correct answer B. In the carotid and aortic bodies

Correct answer C. The partial pressure of oxygen in alveolar air is higher than in the blood

Correct answer C. Breakdown of alveolar walls, reducing surface area and elasticity

Correct answer A. Tar and smoke damage cilia, so mucus collects and must be coughed up

Correct answer D. Nicotine

Correct answer C. Tar

Correct answer B. Inflamed bronchi with excess mucus production and persistent coughing

Correct answer B. Smooth muscle in bronchiole walls contracts and the airways narrow

Correct answer B. Mycobacterium tuberculosis

Correct answer B. Filtering, warming and moistening the inhaled air

Correct answer C. Bronchioles lack cartilage and have smooth muscle in their walls

Correct answer C. Nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

Correct answer C. About one quarter

Correct answer B. It accepts H⁺ ions to form haemoglobinic acid (HHb)

Correct answer A. More red blood cells due to increased erythropoietin secretion

Correct answer B. Slightly lower than atmospheric pressure

Correct answer A. Goblet cells secrete mucus that traps particles and cilia sweep it towards the pharynx

Correct answer B. Simple squamous epithelium

Correct answer B. To lower surface tension and prevent alveoli collapsing